MAP Data Centre Status

Hans Hirter, Atmospheric Science ETH, 8093 Zurich, Switzerland

New MAP Web interface

The MDC Web interface grew into a very complex structure, unfortunately not always in a very user friendly way. With the new concept we return to the roots of the MAP Data Centre definition: to get data over the Internet as easily as possible for the users. This means that in the new concept, the user will reach the data area in fewer clicks than before, while the graphical Web interface is slightly more hidden. Figure 1 shows the revised MAP Data Centre page. The basic frame concept is valid for all the pages. On top you find the main content of the page, on the left the links to the different categories, and in the centre the main information as first display. Subsequently, you will find information or data of the category selected in the centre frame.
In the particular case of SOP, you find the SOP categories on the left and the information about the selected category in the centre. The SOP Homepage is located just one click from the MAP Homepage. Each category has a file and a browser access area. The file access table offers the following columns:
Description, Data Format, FTP location, User feedback, data availability, and remarks. The readme file sent by the providers is linked into the description section. Data changes in the last 10 days are highlighted by a red subcategory. If you need a printout, refer to Tips and Tricks. The section FTP offers a direct FTP link to the data. FTP access is possible by an FTP tool or through a Web browser. On the Web browser there are two protocols available: The FTP protocol (ftp://ftp.sma.ch/outgoing/map/sop/data/) or the HTTP protocol (http://www.map.meteoswiss.ch/sop-img/). It is possible that you encounter problems when attempting to go up to a higher or down to a lower level directory. The reason for this is unclear. There are many different Browsers, Versions and Operating systems, and the most simply solution to circumvent the difficulty is to switch to the other protocol and try again.

MAP Data Centre access statistic

In the last fifteen moths there was a lot of Internet traffic at MDC. On average, the MDC had 1554 requests per day or 690000 accesses in the last fifteen months (counting each single access to a document or image in the entire MAP area). Figure 2 shows the monthly traffic in the last fifteen months. The average data transfer rate per day was 51.1 Mbytes.
The top two browsers with the largest numbers of requests are Netscape with 258000 and Internet explorer with 227000 requests. As for the operating systems, we detected 343000 requests from Windows, 126000 request from UNIX, and 31000 request from Macintosh systems. Based on this, we concluded to develop our Web interface primarily for Netscape and Internet explorer and to give up some fancy features and fonts.

MAP Database and Web server migration

As a consequence of the updating of the operation system (this step was necessary for security reasons) we encountered more and more problems with the stability of the Oracle Web Application Server. The database itself was not on the highest upgrade level, but it run more than 2 years without serious problems. The new Oracle Application Server (iAS) is based on the Apache Web server.
As a first step, the migration took place on the MAP Backup Server (MAP2). Because the new Oracle Web interface works only with newer Oracle databases, we had to migrate the database to Oracle 8i as well. Because of a different internal structure of iAS we had to recompile all programmes. In the next step, we did the same for the MAP Server. The database migration took more than 20 hours; 12 Gbytes were moved to the Oracle 8i database. We ran the migration during a weekend in order to interrupt service as little as possible. We made very every reasonable effort to check as many links as possible in the MAP document area. Nevertheless, there might still be dead links, and we kindly ask you to report any interruption of external links as well as of links within MAP Web pages.
The good news for the users of the MAP Web: The migration is complete! The new Web server is stable and had no crash in the last two months. It is now also possible to use the DODS interface for the netCDF files (http://www.map.meteoswiss.ch/sop-img/flights/electra/access_electra_data.html).

Tips and Tricks

If you print pages with HTML tables, the colours in the cells will be missing on the printout, because background colours are not printable from the Web browser. But you can use Adobe Acrobat (not Adobe Acrobat Reader!) to convert HTML pages to PDF. All of the text, images and links from multiple HTML pages and image files are then included in a single new PDF document. The new PDF document contains the background colours of HTML tables, thus, with Adobe Acrobat you will get a better result than with any Web browser.
If you do a database request for public data (SOP, required) on your Web Browser and you receive the message "The Server had an internal error and could not process the request" or "The page cannot be displayed" after a long time of waiting, you have the possibility to get the data directly by FTP. These errors appear only when the MAP ORACLE database is very busy or when you ask for a big amount of data. You must go back one page on your Web Browser to find out the name of your data file. On the Web Browser form you will find the name under "File output options: Filename". You can try to fetch the data directly by FTP after a while. On your Web Browser you must enter the following command: "http://www.map.meteoswiss.ch/pub-file/" and you will find your file there. If you use an FTP tool, you must first connect to the MAP FTP Server (ftp.sma.ch) with anonymous login. Now you must type in the command "get /pub/map/mappubout/filename" for fetching the data file. For database request in the supplemental area, refer to MAP newsletter 7.